Electric switch



Aug. 14, 1956 T. E. cu RTIS 2,759,076

ELECTRIC SWITCH Filed June 25, 1954 T r; 2| L I K) 5 6 t 4 I44; 25 I: 9 I l 18 l 26d I I INVENTOR FIG. 3

THOMAS E. CURTIS FIG. 4

AT ORNEY United States Patent Orifice 2,759,07i6 Patented Aug. id, 1956 ELECTRIC swlrcn Thomas E. Curtis, Hampton, Ga, assiguor to Southern States Equipment Corporation, a corporation of Georgia Application June 25, 1954, Serial No. 439,277

9 Claims. (Cl. 200-170) This invention relates to electric switches and more particularly to switches of the air break or disconnect type which are provided with magnetic means for augmenting the force by which the separable contacts are maintained in contact making relationship.

The continued growth of electric power systems results in the flow of larger and larger currents through the system components and may produce magnetic effects which cause sufiicient separation of switch contacts under load or fault conditions as to cause pitting of the contact surfaces thereby to interfere further with the flow of current through the switch.

Co-pending application Ser. No. 305,739 filed August 22, 1952, now Patent #2,733,322, Jan. 31, 1956, and assigned to the assignee of this invention, discloses a switch wherein a jaw contact is provided with magnetic means engageable by the tip of a switch blade when the blade is swung into the jaw and rotated about its longitudinal axis.

Co-pending application Ser. No. 307,894 filed September 4, 1952, now Patent #2,732,468, Jan. 24, 1956, and assigned to the assignee of this invention, discloses a switch in which a knife blade swings into and out of engagement with the jaw contact and in which magnetic means for augmenting the contact pressure is mounted on the knife blade. The knife blade is not arranged to rotate about its own longitudinal axis to augment the pressure developed at the contact making surfaces.

A principal object of this invention is to provide an improved electric switch of the air brake or disconnect type which combines the mechanical pressure producing feature of a switch blade arranged to rotate about its longitudinal axis with magnetic pressure producing means operably related with the rotatable blade so as to provide a switch capable of conducting very large currents without causing pitting of the contacting surfaces.

The invention in one form as applied to a switch having a blade which is rotatable about its longitudinal axis and arranged for swinging movement relative to a fixed jaw contact resides in forming the blade with turned back end-portions so as to form a loop circuit, the magnetic action of which tends to establish a predetermined contact pressure when the end portions engage the sides of the associated jaw contact to complete an electric circuit through the switch. According to a feature of the invention, suitable, yieldable supporting means constructed at least in part of insulating material is used to form mechanical reinforcement for the turned back end-portions of the blade.

For a better understanding of the invention reference may be had to the following detailed description taken in conjunction with the accompanying drawings in which Fig. 1 is a top plan view of an electric switch embodying the invention; Fig. 2 is a side view of the switch shown in Fig. 1; Fig. 3 is an end view of the jaw contact end of the switch shown in Figs. 1 and 2; and in which Fig. 4 is an enlarged plan view of the jaw contact end of the switch shown in Figs. 1 and 2.

While the invention is shown in the drawings and described hereinafter as being applied to a switch of the type disclosed and claimed in U. S. Patent 2,520,036 granted August 22, 1950, and assigned to the assignee of this invention, it will be understood that the invention is not limited to a switch of this particular type but is also applicable to other similar switches.

With reference to Figs. 1 and 2, the numeral 1 represents a metallic base member constructed in the form of a channel. Bolted to channel 1 at the left hand end thereof by means of bolts l is an insulator stack 3 to the upper end of which is affixed a jaw contact 4 integrally formed with a terminal stud 5, jaws 4 and stud 5 being secured to insulator stack 3 by means of bolts 6. Jaw comprises spaced elements 4a and 4b. Secured to the right hand end of the base member 1 by means of bolts '7 is an insulator stack 8 to the top end of which is secured by bolts 9 a conducting yoke element 10 which is integrally formed with a terminal stud 11;. The left hand end of yoke element 10 is provided with spaced prongs 12 and 13 which are joined together at their left hand extremities by a vertically disposed journal sleeve 14- which forms the upper journal support for the rotatable insulator stack 15 which at its lower end is rotatably supported by the base 1 through the bearing 16. Rotary movement is imparted to insulator stack 15 by applying an operating force to the radially extending operating rod 17. Securely aifixed to the upper end of insulator stack 15 is an operating crank 18, the bolts 19 being used to interconnect crank 18 to insulator stack 15.

J aw contact 4 and conducting yoke 10 are electrically interconnected by means of a switch blade 20 which is pivotally mounted at 21 on the yoke element 10 for swinging movement relative to jaw contact 4. The pivot 21 comprises a pin which operably interconnects the hinge element 22 with the conducting yoke 10. Switch blade 20 is rotatable about its own longitudinal axis within the hinge element 22. A conducting jumper 14a constructed of flexible material is securely affixed to the switch blade Eli and to the conducting yoke 10, thereby to shunt the major portion of the current around the relatively movable surfaces of the blade 20, hinge 22 and pin 21 together with those portions of yoke 10 which are in contact with pin 21.

In order to impart operating movement to blade 20, an operating force is applied to operating arm 17 thereby to rotate insulator stack 15 and to cause crank 13 to swing about the axis of insulator stack 15 as a center. The right hand extremity of crank 18 is operably related with the right hand extremity of blade 20 by means of a link 23 connected by a pin 24 to blade 20 and connected with crank 1% through the yieldable ball and socket joint schematically represented at 25. Thus operating movement of crank 1%, assuming the switch is in the closed position, first imparts rotary movement to blade 2 about its longitudinal axis there-- by to cause the left hand extremity of blade 24} to disengage the spaced elements of jaw contact 4. Thereafter, continued movement of crank 18 causes the entire switch blade 20 to swing about pin 21, thereby to move out of engagement from spaced elements 4a and 4b of the jaw contact a. in order to close the switch, reverse operating movement applied to crank 17 causes reverse movement of crank 18 thereby initially to swing the blade 2i) down into the space between the elements of jaw contact 4 and thereafter to impart rotary movement to blade 20 about its longitudinal axis thereby to cause the blade tip to engage by pressure engagement the spaced elements in and 4b of jaw contact 4.

Contact pressure at the contacting surfaces is increased or augmented by magnetic means mounted on the switch blade 20 and constructed according to this invention. This magnetic means comprises conducting means forming a loop circuit with the end portions of blade 29. As is best shown in Fig. 3 turned back portions 26:! and 26b are respectively provided with contacting surfaces which are curved or arcuate in shape as respectively indicated at 26c and 26d. The turned back portions 26a and 26b, if desired, may be provided in accordance with the invention with yieldable support means 27 secured by bolt 28 and nut 28a to the blade 20 and insulated therefrom as indicated by the insulating washers 29 and 30. As is best seen in Fig. 4, the extremities of yieldable support element 27 may be respectively secured to the turned back elements 26 and 26b by means of bolts 31 and 32. From Fig. 4 it will be understood that the flow of current in the direction indicated by the arrows results in the formation of a pair of loop circuits, the magnetic elfect of which is to increase the pressure established between the contacting surfaces of the jaw elements 4a and 4b with the respective surfaces 260 and 26d. In this way undersired pitting or erosion of the contacting surfaces is minimized or eliminated entirely and good current-carrying conducting surfaces are maintained so as to prevent undue heating of the contacting elements.

While I have shown and described a particular embodiment of the invention, 1 do not wish to be limited thereto and intend in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric switch comprising a first contact, a switch blade rotatable about its longitudinal axis, magnetic means mounted on said blade and engageable with said first contact to make electric contact therewith, the flow of current through said magnetic means being effective to cause said magnetic means to exert a contact making force against said first contact, and means for rotating said blade about its longitudinal axis while said blade is in proximity to said first contact.

2. An electric switch comprising a first contact, a switch blade rotatable about its longitudinal axis and mounted for swinging movement relative to said first contact, magnetic means mounted on said blade and engageable with said first contact to make electric contact therewith, the flow of current through said magnetic means being effective to cause said magnetic means to exert a contact making force against said first contact, and means for imparting swinging movement to said blade relative to said first contact and for rotating said blade about its longitudinal axis while said blade is in proximity to said first contact.

3. An electric switch comprising a first contact having a pair of spaced elements forming a jaw, a switch blade mounted for swinging movement into and out of the space between said elements and rotatable about its longitudinal axis while disposed between said elements, magnetic means mounted on said blade and engageable with at least one of said elements in response to rotation of said blade while between said elements to establish an electric circuit between said one element and said blade through said magnetic means, the flow of current through said magnetic means being effective to cause said magnetic means to exert a force against at least one of said elements, and means for swinging said blade relative to said first contact and for rotating said blade about its longitudinal axis while disposed between said elements.

4. An electric switch comprising a first contact, a switch blade rotatable about its longitudinal axis and mounted for swinging movement relative to said first contact, conducting means mounted on said blade and engageable with said first contact to establish an electric circuit therebetween, said conducting means being arranged relative to said blade so as to form therewith a loop circuit for conducting at least a portion of the current flow between said first contact and said blade thereby to establish a magnetic force tending to urge said conducting means into contact making engagement with said first contact, and means for imparting swinging movement to said blade and for rotating said blade about its longitudinal axis while said blade is in proximity to said first contact.

5. An electric switch comprising a first contact, a switch blade rotatable about its longitudinal axis and mounted for swinging movement relative to said first contact, conducting means mounted on said blade and engageable with said first contact to establish an electric circuit therebetween, said conducting means being arranged relative to said blade so as to form therewith a loop circuit for conducting at least a portion of current flow between said first contact and said blade thereby to establish a magnetic force tending to urge said conducting means into contact makin engagement with said first contact, yieldable support means mechanically interconnecting said blade and said conducting means and formed at least in part of insulating material so as to prevent the flow of current through said support means, and means for swinging said blade relative to said first contact and for rotating said blade about its longitudinal axis while in proximity to said first contact.

6. An electric switch comprising a first contact, a switch blade rotatable about its longitudinal axis and mounted for swinging movement relative to said first contact, magnetic means mounted on said blade, said magnetic means comprising an end portion of said blade turned back alongside said blade to form therewith a loop circuit, said end portion of said blade being engageable with said first contact in response to rotation of said blade about its longitudinal axis to establish an electric circuit between said blade and said first contact and the magnetic action of said loop circuit being etiective to urge said end portion of said blade into pressure engage ment with said first contact, and means for imparting swinging movement to said blade relative to said first contact and for rotating said blade about its longitudinal axis while in proximity to said first contact.

7. An electric switch comprising a first contact, a switch blade rotatable about its longitudinal axis and mounted for swinging movement relative to said first contact, magnetic means mounted on said blade, said magnetic means comprising an end portion of said blade turned back alongside said blade to form therewith a loop circuit, said end portion of said blade being engageable with said first contact in response to rotation of said blade about its longitudinal axis to establish an electric circuit between said blade and said first contact and the magnetic action of said loop circuit being effective to urge said end portion of said blade into pressure engagement with said first contact, yieldable support means constructed at least in part of insulating material and me chanically interconnecting said blade and said turned back end portion thereof, and means for imparting swinging movement to said blade relative to said first contact and for rotating said blade about its longitudinal axis while in proximity to said first contact.

8. An electric switch comprising a first contact having a pair of spaced elements forming a jaw, a switch blade rotatable about its longitudinal axis and mounted for swinging movement relative to said first contact, triagnetic means mounted on said blade, said magnetic mca comprising a pair of diametrically disposed end portions of said blade turned back alongside said blade to form therewith a pair of loop circuits, said end portions of said blade being engageable respectively with said spaced elements in response to rotation of said blade about its longitudinal axis when said blade is disposed between said elements, and means for imparting swinging move-- ment to said blade relative to said first contact and for rotating said blade about its longitudinal axis while disposed between said spaced elements.

9. An electric switch comprising a first contact having a pair of spaced elements forming a jaw, a switch blade rotatable about its longitudinal axis and mounted for swinging movement relative to said first contact, magnetic means mounted on said blade, said magnetic means comprising a pair of diametrically disposed end portions of said blade turned back alongside said blade to form therewith a pair of loop circuits, said end portions of 10 insulating material and mechanically secured to said blade and to both of said turned back end portions thereof so as to form a resilient support therefor, and means for imparting swinging movement to said blade relative to said first contact and for rotating said blade about its longitudinal axis while disposed between said spaced elements.

References Cited in the file of this patent UNITED STATES PATENTS 1,748,724 Morger Feb. 25, 1930 2,420,074 Froland May 6, 1947 2,695,350 Schultz Nov. 23, 1954 

